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Optical properties of the iron-based superconductor LiFeAs single crystal
- Optical properties of the iron-based superconductor LiFeAs single crystal
- Min, Byeong Hun; Hong, Jong Beom; Yun, Jae Hyun; Iizuka, Takuya; Kimura, Shin-ichi; Bang, Yunkyu; Kwon, Yong Seung
- DGIST Authors
- Kwon, Yong Seung
- Issue Date
- New Journal of Physics, 15
- Article Type
- Dielectric Functions; High Temperature Superconductors; Inter-Band Transition; Iron-Based Superconductors; Low-Temperature Data; Metallic Behaviors; Optical Conductivity; Optical Conductivity Spectra; Plasma Frequencies; Reflectivity Spectra; Semiconductor Quantum Wells; Single Crystals; Superconductivity
- We have measured the reflectivity spectra of the LiFeAs (Tc = 17.6 K) single crystal in the temperature range from 4 to 300 K. In the superconducting (SC) state (T < Tc), the clean opening of the optical absorption gap was observed below 25 cm-1, indicating an isotropic full gap formation. In the normal state (T > Tc), the optical conductivity spectra display typical metallic behavior with the Drude-type spectra at low frequencies, but we found that the introduction of the two Drude components best fits the data, indicating the multiband nature of this compound. A theoretical analysis of the low-temperature data (T = 4 K < Tc) also suggests that two SC gaps best fit the data and their values were estimated as Δ1 = 3.3 meV and Δ2 = 1.59 meV, respectively. Using the Ferrell-Glover-Tinkham sum rule and dielectric function 1 (ω), the plasma frequency of the SC condensate (ωps) is consistently estimated to be 6665 cm-1, implying that about 65% of the free carriers of the normal state condense into the SC condensate. To investigate the various interband transition processes (for ω > 200 cm-1), we have also performed the local-density approximation band calculation and calculated the optical spectra of the interband transitions. This theoretical result provided qualitative agreement with the experimental data below 4000 cm-1 . © IOP Publishing and Deutsche Physikalische Gesellschaft.
- Institute of Physics Publishing
- Related Researcher
Kwon, Yong Seung
Quantum Functional Materials Laboratory
High Tc Superconductors and magnetic materials; Thermoelectric Materials
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- Department of Emerging Materials ScienceQuantum Functional Materials Laboratory1. Journal Articles
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